Image processing techniques comprising histogram processing, such as histogram equalisation is known within the art. Histogram processing may serve many different purposes, for instance enhancing the contrast of an image. The theory of histogram equalisation and matching are well known, and for a continuous signal it is theoretically possible to obtain perfect histogram equalisation or a match to a specific distribution. Using the same approach it is possible to obtain an approximate equalisation/match for a discretised histogram. It is furthermore known to apply processing of the chrominance of a video signal in order to attain optimal perceived quality of a colour image for instance on a television screen.